You can get a windowpane in whole wheat dough.

This picture is from a 100% whole wheat, rather high hydration dough. It had been kneaded for about 20 minutes at speed 2 in a Delonghi/Kenwood mixer. The lighting isn't that great, but if you look at the base of the left thumb, you'll see a fingertip behind the dough. The browner areas are simply dough that has not been stretched. This started as a piece of dough about the size of a golf ball And yes, it made nice bread - in this case a light sandwich loaf.